Purification of naphthalene



Patented Apr. 7, 1931 UNITED .STATES PATENT OFFICE onone sonnonrnnjor' BERLIN, GERMANY, ASSIGNOR T NEWPORT mnnurnc'runmo COMPANY, or CARROLLVILLE, WISCONSIN, A CORPORATION or DELA ARE runrrrcn'rron or NAPHTHALENE' No Drawing. Original application filed August 29, 1921, SerialNo. 496,639, and in Germany February 24, 1915. Divided and this application filed March 2a, 1925.

I have filed applications, in Germany February 24, 1915 (Patent No. 324,861 issued to assignee, Tetralin G. 111. b. in Germany December 7 1915 (Patent No. 324,862 issued to. assignee, Tetralin G. 111. b. H.) in Germany May 13, 1916 (Patent No. 324,863 issued to assignee,Tetral in G. m. b. H.) and in Belgium, filed Ma 31, 1920; in France filed May 21,1920 in reat Britain filed July 8, 1920; in Italyfiled June 30,1920; in Austriafiled April 15, 1920; in Hungary filed July 31, 1917; in the Netherlands filed April 21, 1920; in Switzerland, filed June 30, 1920, and in Czechoslovakia filed July 10, 1920.

The present invention relates to purification of commercial naphthalene, and particularly to a purification thereof to-an extent sufficient to remove therefrom elements which act as catalyzer poisons when naphthalene is subjected to hydrogenation in the presence of a catalyst. The present application is a division of my copending application Ser. No.

496,639, filed August 29th,.1921, which was on April 27th, 1926, as Patent It has long been known that even the purest commercial (i. e. technically produced) naphthalene stubbornly. retains certain small amounts of impurities, especially methylated coumarone and corresponding sulfur compounds, which substances cause a red coloration when. commercial naphthalene is sub jected to treatment with concentrated sulfuric acid. It was also known that by boiling commercial naphthalene with acetate of mercuryin alcoholic solution, certain mercury compounds were produced which were not mercury compoundsof thionaphthalene. It has also previously been known that ordinary purified naphthalene contains sulphur compounds and it has been proposed to purify naphthalene from these sulfur compounds by repeated crystallization from various organic solvents: Such processes would, however, not be commercially feasible in connection with the commercial hydrogenation of naphthalene. i

In accordance withthe present invention, the naphthalene treated, namely, commercial or technical naphthalene, can be purified by stances or other materials of Serial No. 19,144.

causeundesired side reactions, for example, in

vacuo. This purifibation may sometimes not be sufficiently complete and a more complete purification can beeffected by the use, instead of the above mentioned porous materials alone, of fullers earth, upon Which is precipitated a small amount, say, 1 or2 percent or so, of reducedtnickel, reduced iron or other like metal. Although I am aware that a number of apparently unrelated metals will eflect a similar purification, I am unable to classify them generically so that they will fall into a natural group. During this purification step, it is advisable to agitate by stirring, pumping, etc. in the presence of hydrogen. The temperature in this operation should be kept above 100C. 1

These metals also can be used alone in a finelydivided state for the purification of naphthalene.

Another method of purifying the naphthalene, which reduces the impurities to a very small quantity, involves the treatment of the molten naphthalene with small percentages of metallic sodium or potassium or other easilymelted metals of like properties. In this operation it is advisable to treat the molten naphthalene with, say, from one-half to one Examples of such compounds are the metalsodium or potassium amid), metal carbides (such as aluminium or calcium carbides), or othermetal compounds of acetylene.

It is of course, to-be understood that these various methods of purification above given. can be used each by itself, 'or two or more ofthese methods can be used in conjunction with each other.

Naphthalene purified according, tothe thalene containing appreciable amounts of above processes does not produce any red coloration when treated with concentrated sulfuric acid. If it is found that thepurification of a particular batch has not been sufficiently completed, it-is advisable toagain subject this material to a retreatment according toone or the other of the above mentioned processes.

The naphthalene, after its purification, canbe separated fromthe residue'of the purifying agents, or from the compounds pro- -duced by theunion of the impurities with the purifying agents, by hot pressure filtration in hydrogen, or by distillation'at a relatively low temperature, distillation in vacuo being a preferred mode ofoperation.

The purified naphthalene can then be subjected to hydrogenation in the presence of finely-divided nickel as a catalyst, or-otherwise-in accordancewith the methods set forth in my application above referred to, without injury t'othe catalyst. It may be added that thepurificat'ion of naphthalene from thosesubstances which produce red coloration upon treatment with sulfuric acid, not only makes the catalyzer last better, that is to say retain its usefulness for along period, but also renders the hydrogenation of the naphthalene much easier and more readily controlled.

The 'higl' ly impure varieties of naphtha.-

lene which give a deep red color with sulfuric acid,can be purified" according to the processes herein described, and subsequently hydrogenated.

The following is an illustrative example of themethodembraced by the present invention, but is by no means to be taken as a limitation of its scope.

I Example-400 kilos of commercial naphthalene in a kettle at a temperature above 100' (l, are stirred with to or more of finely divided absorbent earth, until a sample of the material, after being substantially separated, shows no red coloration. when treated. with concentrated sulfuric acid, after standing for some time.

It is to be understood that, while I have mentioned certain preferred substances through the. use of which my invention may be carried into effect, I doinot limit my in- Ventionto the use of these specific substances.

Itis to bef-urther-understood' that in the following claims the' term-porous: material, is

intended to include and to be limited to the porous materials which have been mentioned in the specification. These materials are: finely divided porous materials which naturally contain small quantities of metal oxides, such as lime, and which'material is also capable of absorbing or adsorbing coloring mat ter, resinous substances, or othermaterial of high molecular weight.

I claim:

1 A. process for the purification of naphimpurities capable of producing ared coloration on treatment with concentrated sulfuric acid, which comprises treating such naphthalene at above its melting point with aiporous material containing small quantities ofmetal oxidesand': separating the naphthalenetherefrom. I

2. In the process ofpurifying naphthalene to remove catalyzer poisons the step which lene at above its melting point with a aorous material containing small quantities of metal oxides and separating the naphthalene therefrom bydistillation. 1

4. A process for the purification of'naphthalene containing appreciable amounts of impurities capable of producing a red coloration on treatment withconcentrated sulfuric acid, which comprises treating such naphthalene at above its'melting point with absorbent earth containing small quantities of metal oxidesand the-n separatingthe naphthalene from the absorbent earth.

5'. A process for the purification of naphthalene containing appreciable amounts of impurities capable of producing axred coloration on treatment with concentrated sulfuric acid, which comprises treating such naphthalene at above its melting point with a porous material containing smallquantities of metal oxidesand a finely divided metal having an affinity for sulphur andsulphur compounds and separating the naphthalene.

6.1 n the process of purifying naphthalene to remove catalyzer poisons, the'st'ep which comprises treating naphthalene in the fluid condition with a porous materialcontaining small quantities of metal: oxides and a finely divided metalhaving-an-aflinity for sulphurand sulphur compoundsh 7. A process for-thepurification of naphthalene containing appreciable amounts of impurities capable of producinga red color ation onv treatment with. concentrated; sulfuric; acid-,which comprises treating such naphthalene at, above-it'smelt-ing pointwith a porous material containing small quantities of metal oxides and a finely divided metal having an aiiinity for sulphur and sulphur compounds and separating the naphthalene therefrom by distillation.

8. A process for the purification of naphthalene containing appreciable amounts of impurities capable of producing a red coloration on treatment with concentrated sulfuric acid, which comprises treating such naphthalene at above its melting pointwith absorbent material containing small quantities of metal oxides and a finely divided metal having an afiinity for sulphur and sulphur compounds, and then separating the naphthalene from the absorbent earth.

9. The process for the purification of naphthalene containing appreciable amounts of impurities capable of producing a red coloration on'treatment with concentrated sulfuric acid, which comprises treating suchnaphthalene at above its melting pointwith a porous material containing small quantities of metal oxides and a finely divided metal having an affinity for sulphur and sulphur compounds, in the presence of hydrogen, and separating the naphthalene.

10. In the process of purifying naphthalene to remove catalyzer poisons, the step which comprises treating naphthalene in the fluid condition with a porous material containing small quantities of metal oxides and a finely divided metal having an afiinity for sulphur and sulphur compounds, in the presence of hydrogen.

11. A process for the purification of naphthalene containing appreciable amounts of impurities capable of producing a red coloration on treatment with concentrated sulfuric acid, which comprises treating such naphthalene at above its melting point with a orous material containing small quantities 0 metal oxides and a finely divided metal having an affinity for sulphur and sulphur compounds in the presence of hydrogen, and separating the naphthalene therefrom by distillation.

12. A process for the purification of naphthalene containing appreciable amounts of impurities capable ofproducing a red coloration on treatment with concentrated sulfuric acid, which comprises treating such naphthalene at above its melting point with absorbent earth containing small quantities of metal oxides and a finely divided metal having an affinity for sulphur and sulphur compounds, in the presence of hydrogen, and then separating the naphthalene from the absorbent earth. a

In testimony whereof I have signed my name to this specification.

GEORG SCHROETER. 

